1. Field of the Invention
This invention relates to a method of and compositions for removing films from hard surfaces, such as glass surfaces. In particular, this invention relates to the removal of films formed by plasticizers and the like materials which accumulate on interior glass window surfaces and impair visibility. Such films are particularly hazardous to drivers of motor vehicles as dust and tobacco smoke particles embedded in the film cause a glare which obstructs the driver's view. This is particularly true at night when the light source is the headlights of an approaching motor vehicle, or when the sun is at a low elevation and in the driver's eyes.
2. Description of the Prior Art
Various compositions and methods for cleaning surfaces, and in particular, glass surfaces have been described in the prior art. U.S. Pat. No. 3,354,089 describes a windshield washing composition which when applied to wet strengthened paper wipers, cleans the glass surfaces and deposits an invisible yet dirt-adhesion resistant film. This patent also points out that the detergent chemicals used in the cleaning composition must not leave a visible or light diffracting film obstructing the driver's visibility. It is also clear from the patent that the glass surface exterior to the driver is being cleaned.
A windshield cleaning composition having as an essential ingredient an amine and having particular utility for cleaning automobile windshields is described in U.S. Pat. No. 3,309,321. This patent describes that it is well known to those who operate automobiles that a scum or film can form on automobile windshields which will obscure the vision. One of the components of this film or scum is said to be dibutyl phthalate which is believed to be deposited on the windshield from the wiper blade. Dibutyl phthalate is a plasticizer contained in the wiper blade. Again, it is clear that the surface of the windshield exterior to the driver is being described.
U.S. Pat. No. 2,611,747 discloses a windshield cleaning composition containing an alcohol or ketone, and naphthalene. It is clear from the disclosure that the cleaner is an aqueous solution, i.e., a solution containing not less than 50% water, and that the organic components of the solution do not exceed 26%.
U.S.S.R. Inventors Certificate 288,206 teaches a windshield solution containing acetone, isoamyl acetate, ethyl alcohol, and a small amount of nonvolatiles. Again, it is clear from the text that the cleaner is an aqueous solution containing no more than 9.5% organic solvents, the balance being water.
The glass cleaning compositions cited above, in addition to several commercially available window cleaners whose compositions are representative of the liquid glass cleaners marketed today were tested for their phthalate dissolving capacities (see Table 2A), and for their glass cleaning effectiveness (see Tables 4B and 4C). It was found that both the commercially available cleaners and the prior art compositions could not dissolve any phthalate plasticizers at all, and that they leave an undesirable haze on the glass surface when used to clean phthalate films from glass test panels.
Thus, at the present time, no commercial cleaners or prior art compositions can remove phthalate films from the interior surfaces of automotive window glass without leaving an undesirable haze thereon.